BAGHDAD (Reuters) -- A series of blasts in Baghdad killed 95 people and wounded 536 in Iraq's bloodiest day this year, prompting a rare admission of culpability from Iraqi security forces struggling to cope without U.S. help.
At least six blasts struck near government ministries and other targets at the heart of Iraq's Shi'ite-led administration, weeks after U.S. combat troops withdrew from urban centers in June, thrusting Iraq's security forces into the lead role.
"We must face the facts. We must admit our mistakes, just as we celebrate our victories," Defense Ministry spokesman Major General Mohammed al-Askari told a group of U.S. and Iraqi military officials.
His comments echoed earlier remarks by Baghdad's security spokesman, Major General Qassim al-Moussawi.
"This operation shows negligence, and is considered a security breach for which Iraqi forces must take most of the blame," Moussawi told Iraqiya state television.
His office said 10 Baghdad security officials had been detained pending an investigation into security breaches.
The sectarian war that savaged Iraq after the 2003 U.S. invasion has abated and Iraq celebrated the restoration of its sovereignty in June when U.S. troops withdrew from cities.
The government this month ordered most blast walls in Baghdad to be removed within 40 days, a sign of faith in its troops and police before a national election in January. But the coordinated attacks on August 19 on heavily guarded targets shattered a growing sense of optimism about Iraq's stability.
"We will continue to assist the Iraqis in securing their country until the agreements denote that it's time for us to go," White House spokesman Robert Gibbs told reporters. A U.S.-Iraqi security pact stipulates a U.S. withdrawal by 2012.
The statement seemed to lessen chances of a slightly accelerated withdrawal, raised as a possibility by U.S. Defense Secretary Robert Gates after a visit to Iraq last month.
In one blast, a massive truck bomb close to a checkpoint for the heavily fortified Green Zone blew out the windows of the Foreign Ministry. Dozens were mown down in a blizzard of glass.
"The windows of the Foreign Ministry shattered, slaughtering the people inside. I could see ministry workers, journalists, and security guards among the dead," said a distraught ministry employee who gave her name as Asia.
The attacks could undermine confidence in Prime Minister Nuri al-Maliki before the parliamentary election, and could also deter foreign investors, especially oil companies.
Maliki called an emergency meeting to reevaluate the defense of Baghdad. He said in a statement that the attacks were aimed at "raising doubts about our armed forces, which have proven themselves very capable of confronting terrorists."
Analysts and members of the public disagreed.
"Today's attacks reveal a major deficiency and weakness of the security forces. They were organized and huge," said analyst Hameed Fadhel of Baghdad University.
Baghdad's normally busy streets emptied, and the few people still outside poured scorn on the security forces.
"The security forces don't provide security, they just cause traffic," laborer Haythem Adil said.
No group claimed responsibility, but Moussawi said two members of Al-Qaeda were arrested when another car bomb was intercepted. Iraqi television later showed a truck loaded with water tanks stuffed with explosives that had been disarmed.
Sunni Islamist groups like Al-Qaeda consider Shi'ites heretics, and have been blamed for a series of blasts in the last two months at mostly Shi'ite venues like mosques.
Iraqi politicians and other officials have accused neighboring states of fomenting violence in Iraq. Analysts say that could be a ploy to detract blame from domestic failings.
The second truck bomb in Baghdad's Waziriya district close to the Finance Ministry killed at least 28 people and caused huge destruction. Part of a raised highway nearby collapsed.
"Suddenly a powerful blast shook the building...Most employees were wounded by flying glass and others, including me, suffered concussion," said ministry worker Batoul al-Amri.
Another explosion was close enough to Reuters' offices in central Baghdad's Karrada district to burst open windows and doors. Columns of smoke could be seen rising from several sites.
The Baghdad provincial government building came under mortar attack, police said, as did the Salhiya district in central Baghdad, home to army bases and a television station.
At least one suspected mortar round landed near the United Nations compound in the Green Zone, startling UN workers marking the sixth anniversary of the destruction of their previous Baghdad headquarters by a truck bomb which killed envoy Sergio Vieira de Mello and other staff, UN guards said.
The U.S. military said it had no reports of mortar fire.
In Bayaa, in southern Baghdad, a blast killed two people.